Benadryl cream is excellent for stopping the itch. It has both an antihistamine in it and zinc, which is an antioxident.
Eczema shows an increase in free radicals in the body due to different possible factors, including stress. The way to lower the free radicals is by increasing antioxidents, such as beta carotene and zinc. One person who posts here got well from eczema after juicing watermelon. Watermelon is high in beta carotene. I got well after taking a zinc supplement (30 mg.) You should be getting at least 30 mg of zinc a day, either through food or supplements. Focus on eating foods that are high in antioxidents, including Vitamin E. Sunflower seeds are high in vitamin E, as are other seeds and nuts.
You may also be allergic to the soap or detergent that you are using in the shower and to wash your clothes. You may want to switch to a hypo-allergenic soap such as Dove for sensitive skin, and use fragrance free detergents for the wash, such as fragrance free Tide and Downy.
I also used a creme very successfully called Doctor's Defense. It has Chinese herbs in it, but it's very expensive ($36, including shipping and handling for a little jar), so I'd start with the Benadryl creme since you have such a large area to treat.